5047 don't use atomic_*_nv if you discard the return value

Reviewed by: Garrett D'Amore <garrett@damore.org>
Reviewed by: Jason King <jason.brian.king@gmail.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>

Author: Josef 'Jeff' Sipek

usr/src/uts/common/fs/zfs/dbuf.c

@@ -1605,7 +1605,7 @@ dbuf_clear(dmu_buf_impl_t *db)
 	dndb = dn->dn_dbuf;
 	if (db->db_blkid != DMU_BONUS_BLKID && MUTEX_HELD(&dn->dn_dbufs_mtx)) {
 		avl_remove(&dn->dn_dbufs, db);
-		(void) atomic_dec_32_nv(&dn->dn_dbufs_count);
+		atomic_dec_32(&dn->dn_dbufs_count);
 		membar_producer();
 		DB_DNODE_EXIT(db);
 		/*
@@ -1781,7 +1781,7 @@ dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid,
 	ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
 	    refcount_count(&dn->dn_holds) > 0);
 	(void) refcount_add(&dn->dn_holds, db);
-	(void) atomic_inc_32_nv(&dn->dn_dbufs_count);
+	atomic_inc_32(&dn->dn_dbufs_count);
 
 	dprintf_dbuf(db, "db=%p\n", db);
 
@@ -1827,7 +1827,7 @@ dbuf_destroy(dmu_buf_impl_t *db)
 			dn = DB_DNODE(db);
 			mutex_enter(&dn->dn_dbufs_mtx);
 			avl_remove(&dn->dn_dbufs, db);
-			(void) atomic_dec_32_nv(&dn->dn_dbufs_count);
+			atomic_dec_32(&dn->dn_dbufs_count);
 			mutex_exit(&dn->dn_dbufs_mtx);
 			DB_DNODE_EXIT(db);
 			/*
@@ -2111,7 +2111,7 @@ dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag)
 			 * until the move completes.
 			 */
 			DB_DNODE_ENTER(db);
-			(void) atomic_dec_32_nv(&DB_DNODE(db)->dn_dbufs_count);
+			atomic_dec_32(&DB_DNODE(db)->dn_dbufs_count);
 			DB_DNODE_EXIT(db);
 			/*
 			 * The bonus buffer's dnode hold is no longer discounted

usr/src/uts/common/fs/zfs/dmu.c

@@ -284,7 +284,7 @@ dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **dbp)
 	/* as long as the bonus buf is held, the dnode will be held */
 	if (refcount_add(&db->db_holds, tag) == 1) {
 		VERIFY(dnode_add_ref(dn, db));
-		(void) atomic_inc_32_nv(&dn->dn_dbufs_count);
+		atomic_inc_32(&dn->dn_dbufs_count);
 	}
 
 	/*

usr/src/uts/common/inet/sctp/sctp_addr.c

@@ -137,7 +137,7 @@ sctp_ipif_inactive(sctp_ipif_t *sctp_ipif)
 	rw_destroy(&sctp_ipif->sctp_ipif_lock);
 	kmem_free(sctp_ipif, sizeof (sctp_ipif_t));
 
-	(void) atomic_dec_32_nv(&sctp_ill->sctp_ill_ipifcnt);
+	atomic_dec_32(&sctp_ill->sctp_ill_ipifcnt);
 	if (rw_tryupgrade(&sctps->sctps_g_ills_lock) != 0) {
 		rw_downgrade(&sctps->sctps_g_ipifs_lock);
 		if (sctp_ill->sctp_ill_ipifcnt == 0 &&
@@ -884,7 +884,7 @@ sctp_move_ipif(ipif_t *ipif, ill_t *f_ill, ill_t *t_ill)
 	ASSERT(sctp_ipif->sctp_ipif_ill == fsctp_ill);
 	sctp_ipif->sctp_ipif_ill = tsctp_ill;
 	rw_exit(&sctp_ipif->sctp_ipif_lock);
-	(void) atomic_dec_32_nv(&fsctp_ill->sctp_ill_ipifcnt);
+	atomic_dec_32(&fsctp_ill->sctp_ill_ipifcnt);
 	atomic_inc_32(&tsctp_ill->sctp_ill_ipifcnt);
 	rw_exit(&sctps->sctps_g_ipifs_lock);
 	rw_exit(&sctps->sctps_g_ills_lock);
@@ -1097,7 +1097,7 @@ sctp_update_ipif_addr(ipif_t *ipif, in6_addr_t v6addr)
 			sctps->sctps_g_ipifs_count--;
 			rw_destroy(&osctp_ipif->sctp_ipif_lock);
 			kmem_free(osctp_ipif, sizeof (sctp_ipif_t));
-			(void) atomic_dec_32_nv(&osctp_ill->sctp_ill_ipifcnt);
+			atomic_dec_32(&osctp_ill->sctp_ill_ipifcnt);
 		}
 	}
 
@@ -1209,7 +1209,7 @@ sctp_update_ipif(ipif_t *ipif, int op)
 		sctps->sctps_g_ipifs_count--;
 		rw_destroy(&sctp_ipif->sctp_ipif_lock);
 		kmem_free(sctp_ipif, sizeof (sctp_ipif_t));
-		(void) atomic_dec_32_nv(&sctp_ill->sctp_ill_ipifcnt);
+		atomic_dec_32(&sctp_ill->sctp_ill_ipifcnt);
 		if (rw_tryupgrade(&sctps->sctps_g_ills_lock) != 0) {
 			rw_downgrade(&sctps->sctps_g_ipifs_lock);
 			if (sctp_ill->sctp_ill_ipifcnt == 0 &&
@@ -2029,7 +2029,7 @@ sctp_free_ipifs(sctp_stack_t *sctps)
 			list_remove(&sctps->sctps_g_ipifs[i].sctp_ipif_list,
 			    sctp_ipif);
 			sctps->sctps_g_ipifs_count--;
-			(void) atomic_dec_32_nv(&sctp_ill->sctp_ill_ipifcnt);
+			atomic_dec_32(&sctp_ill->sctp_ill_ipifcnt);
 			kmem_free(sctp_ipif, sizeof (sctp_ipif_t));
 			sctp_ipif =
 			    list_tail(&sctps->sctps_g_ipifs[i].sctp_ipif_list);

usr/src/uts/common/io/comstar/port/fct/discovery.c

@@ -1160,7 +1160,7 @@ fct_register_remote_port(fct_local_port_t *port, fct_remote_port_t *rp,
 		iport->iport_rp_slots[rp->rp_handle] = irp;
 		atomic_or_32(&irp->irp_flags, IRP_HANDLE_OPENED);
 	}
-	(void) atomic_inc_64_nv(&iport->iport_last_change);
+	atomic_inc_64(&iport->iport_last_change);
 	fct_log_remote_port_event(port, ESC_SUNFC_TARGET_ADD,
 	    rp->rp_pwwn, rp->rp_id);
 
@@ -1205,7 +1205,7 @@ fct_deregister_remote_port(fct_local_port_t *port, fct_remote_port_t *rp)
 		atomic_and_32(&irp->irp_flags, ~IRP_HANDLE_OPENED);
 		iport->iport_rp_slots[rp->rp_handle] = NULL;
 	}
-	(void) atomic_inc_64_nv(&iport->iport_last_change);
+	atomic_inc_64(&iport->iport_last_change);
 	fct_log_remote_port_event(port, ESC_SUNFC_TARGET_REMOVE,
 	    rp->rp_pwwn, rp->rp_id);
 

usr/src/uts/common/io/trill.c

@@ -1113,7 +1113,7 @@ trill_node_unref(trill_inst_t *tip, trill_node_t *tnp)
 		if (tnp->tn_tsp != NULL)
 			trill_sock_unref(tnp->tn_tsp);
 		trill_node_free(tnp);
-		(void) atomic_dec_uint_nv(&tip->ti_nodecount);
+		atomic_dec_uint(&tip->ti_nodecount);
 	}
 }
 

usr/src/uts/i86pc/os/cmi_hw.c

@@ -1420,7 +1420,7 @@ cmi_hdl_rele(cmi_hdl_t ophdl)
 	cmi_hdl_impl_t *hdl = IMPLHDL(ophdl);
 
 	ASSERT(*hdl->cmih_refcntp > 0);
-	(void) atomic_dec_32_nv(hdl->cmih_refcntp);
+	atomic_dec_32(hdl->cmih_refcntp);
 }
 
 void
@@ -1431,7 +1431,7 @@ cmi_hdl_destroy(cmi_hdl_t ophdl)
 
 	/* Release the reference count held by cmi_hdl_create(). */
 	ASSERT(*hdl->cmih_refcntp > 0);
-	(void) atomic_dec_32_nv(hdl->cmih_refcntp);
+	atomic_dec_32(hdl->cmih_refcntp);
 	hdl->cmih_flags |= CMIH_F_DEAD;
 
 	ent = cmi_hdl_ent_lookup(hdl->cmih_chipid, hdl->cmih_coreid,